What is Package Dyeing?
Package dyeing is a method of dyeing in which the liquor is circulated radially through a wound package. Usually package dyeing denotes for dyeing of yarn that has been wound on perforated solid dyeing tubes or cones. This helps in forcing the dye liquor through the package. With the start of dyeing cycle, the dye liquor goes on circulating throughout the vessel and tank. This happens till all the dye is used up or fully exhausted. The dye flows through to the yarn package with the help of the deliberate perforations in the tube package. Once full exhaustion is brought about, the carrier of colored yarn is consequently removed from the vessel. A large centrifuge removes excess water from the packages. Finally the yarn is dried using an infra red drying oven.
Figure 1: Vertical loading package dyeing machine
Nowadays package dyeing machine is the most widely used for dyeing of almost all type of yarns, due to economical, automatic and accurate dyeing results. A series of technical developments in the recent years has resulted into package dyeing being developed into a highly sophisticated as well as an economic process. Latest design package dyeing machines are amenable to accurate control and automation. These features would likely to lead to increases in the application of package dyeing.
In most package dyeing machinery the dye liquor is pumped through the tube and the yarn assembly of the package, which consists of a three- dimensional shape with the interstitial space filled with the dye liquor.
Package dyeing machines are available either as vertical loading, as shown in Figure 1, or as horizontally loading machine as shown in Figure 2 that do not require heavy lifting gear to load the packages.
Different Types of Package Dyeing Machine: Different types of package dyeing machines are
Vertical Kier Dyeing Machines
Horizontal Kier Dyeing Machines
Tubular Dyeing Machines
a) Vertical Kier Dyeing Machine:
These machines have a vertical cylindrical dyeing kier, in which material loaded into carriers with vertical perforated spindles, is dyed. The machine could be fully flooded or air pad type. These are high pressure machines and suitable up to 135°C temperature dyeing.
b) Horizontal HTHP Dyeing Machine:
These machines are similar to vertical type machines in which the cylindrical dyeing kier is in horizontal position. The dyeing carriers with vertical spindles are used in these machines, which are inserted into the machine via trolleys. These machines are erected at the ground level and hence do not need an overhead hoist as well as platform, thus making the dye house design and layout is simple.
c) Tubular HTHP Dyeing Machine:
These machines may be of vertical or horizontal type, and have one or many tubes acting as small dyeing vessels, each with a single individual spindle. The spindle is taken out of the tube, loaded and then inserted back into it. These machines can be operated either fully loaded tubes or to partial loads by using dummies. Since all individual tubes in a machine are connected and serviced by a main pump, therefore it is also possible to operate as many tubes as required and disconnecting others.
These machines can be erected at ground level and hence do not need a platform or hoist. These machines are most flexible as for as the capacity variation is concerned, without altering the material to liquor ratio.
In its simplest form a package-dyeing machine is a vessel capable of containing packages of textile material through which heated dye liquor is passed by means of a circulation pump. Later developments accelerated by the need to dye polyester at temperatures above the boil lead to enclosing and strengthening such vessels so that they could operate up to 140°C at pressures around 70 psi (4.95 kg/cm2).
Accessories were added to allow samples to the extracted without depressurizing the whole system and to inject dyes and chemicals from out with the main circulation circuit. Later still, simple controls of time and temperature were replaced with fully automatic programmes based on sophisticated microprocessors that reduced operator involvement in the dyeing process to a minimum and elevated limits of accuracy sophistication previously unattainable levels.
Working Principle of Package Dyeing Machine:
The material to be dyed is wound on the dye springs, perforated plastic cheeses or steel cones and loaded in the carrier spindles, which are compressed and bolted at the top to make a uniform and homogeneous dyeing column. The liquor containing dyes chemical and auxiliaries is forced through with the help of pump, and circulated through the material from inside –out and is reversed periodically so that each and every part of the material get the same and uniform treatment. The dyeing cycle is controlled through a micro computer and different chemicals may be added through the injector pump or color kitchen at any stage of dyeing.
Figure 3: Package dyeing process
In case of fully flooded machines, the liquor expands with the rise in temperature (approximately 5% volume increases from 30-130 degree centigrade temperature) is taken back in the expansion tank through a back cooler. This extra water is then again injected to the dyeing vessel through an injector pump. Expanded volume of the dye liquor is thus remains in continuous circulation in the system.
Any type of addition can be done to the machine through the injector pump, the quantity and time of injection can be controlled through the programmer.
In case of air pad machines, the air above the liquor acts as a cushion, which is compressed with the increase in liquor volume, the pressure is controlled by pre set pressure control valve. In air pad machines have an advantage, that entire dye liquor participate in dyeing and dye exhaustion is perfect. In case some addition has to be done in air pad machines, if the machine temperature is less than 80 degrees, the liquor is taken back by back transfer valve to addition tank, and injected back to machine vessel. If the machine temperature is above 80 Degree then cooling has to be done to bring down the machine temperature.
Air pad technology is possible in all types of machines such as vertical kier, horizontal kier and tubular dyeing machines. The material after dyeing is washed and finished properly in the same machine and taken out hydro extracted or pressure extracted in the same machine and dried subsequently.
Besides, after the dyeing process is completed, the packages are dried either by using a radio frequency machine or a pressure drying machine. In radio‐frequency drying the packages are placed on a polypropylene conveyor belt, which carries them through the drier. The power rating used depends on the fiber type: for wool and cotton it is about 50 kW, whilst for a more hydrophobic fiber such as polyester, it is about 40 kW. Care also has to be taken with acrylic fibers with their low Tg value, so a power of about 30 kW is used for them. In pressure drying the complete frame holding the packages on their spindles can be lowered into the machine and warm air forced through in the same way as the dye liquor was during the dyeing cycle.
Advantages of Package Dyeing Machine:
Package dyeing methodologies have been subjected to intensive research and development. As a result package dyeing machine has evolved into a very sophisticated apparatus. It offers a number of advantages.
Considerable reduction in yarn handling.
Compatible to automatic control, in the process leading to reproducible dyeing.
Open to large batches.
High temperature dyeing a possibility.
Low liquor ratios, giving savings in water, effluent and energy.
Uniform and High rates of liquor circulation, that leads to level application of dyes. Machinery totally enclosed resulting in good working conditions at the dye-house.
References:
Amin, Md. Tanjin. “Overview of a Knit-Dyeing Factory with Necessary Production Formulas.” Global Journal of Research In Engineering 14 (2014): n. pag.
Textile Dyeing By Dr. N. N. Mahapatra
Modelling, Simulation and Control of the Dyeing Process By R. Shamey and X. Zhao
Control Systems in Textile Machines By G. Nagarajan and Dr. G. Ramakrishnan
An Introduction to Textile Coloration: Principles and Practice By Roger H. Wardman
Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. Mr. Kiron is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.
